Method of converting power takeoff assembly to include selectively controlled multiple power takeoff shafts

ABSTRACT

A vehicle transmission assembly includes a power means, a clutch connected to the power means and having an output power shaft, and a plurality of gears and substantial alignment. The gears include a first gear on the power shaft meshed with a second gear mounted on a first idler shaft. The second gear driving a third gear mounted on another idler shaft. The third gear drives a fourth gear mounted on a first PTO shaft. A second PTO shaft is operatively connected to the first shaft. A three position selector assembly on the first shaft selectively powers the PTO shafts simultaneously or individually. The method of connecting a single PTO shaft transmission assembly includes adding a second PTO shaft to said power means, and imposing a multi-position selector assembly to the gears to permit said PTO shafts to be operated together or individually.

CROSS REFERENCE OF RELATED APPLICATION

This application is a divisional of applicant's application Ser. No.08/837,209 filed Apr. 14, 1997 now U.S. Pat. No. 5,901,605.

BACKGROUND OF THE INVENTION

This invention relates to the field of tractors and similar equipmentwherein one or more power takeoff (PTO) shafts are utilized. Moreparticularly, this invention relates to a PTO driving assembly whichallows a base unit having only a mid PTO to be produced and efficientlyconverted later to a unit having both a mid PTO shaft and a rear PTOshaft. The PTO shafts in the converted unit can be selectively activatedseparately or in combination.

Power takeoff shafts are well known. PTO shafts are used on large,medium and small horsepower tractors for a variety of reasons. On someconventional tractors, a PTO shaft extends rearwardly from the powerplant or transmission to supply rotary power to equipment towed behindthe tractor. On other tractors, a mid PTO shaft extends from the middleportion of the tractor to operate equipment, such as a mower deck,located thereunder.

Recently, tractor transmissions which have both mid and rear PTO shaftshave been developed. Both the mid and rear PTO shafts, when engaged,rotate whenever the engine or transmission rotates. Frequently, thecustomer or end user does not always want both PTOs to operate all ofthe time.

Some manufacturers incorporate a selector mechanism into thetransmission so the user can select which PTO shaft to activate. Thecost of the base machine increases when the selector mechanism isincorporated. Not all customers may need, want or be willing to pay forthe higher cost units. These market pressures may force the manufacturerto produce two different models, one providing the mid PTO shaft onlyand another model providing both mid and rear PTO shafts. Themanufacturer incurs higher production and inventory costs. Distributorsand dealers also face higher inventory costs when they stock bothmodels.

Therefore, a primary object of this invention is a provision of a PTOdriving assembly which is an improvement over existing PTO drivingassemblies.

A further object of the present invention is a provision of a PTO shaftdriving assembly wherein the mid PTO and rear PTO shafts are selectivelyrotatable (together or individually) depending upon the position of athree-position selector mechanism.

A further object of this invention is a provision of a PTO drivingassembly which allows the manufacturer to provide a low cost base unitwith mid PTO only and a conversion kit which can be utilized anytimeafter the initial assembly to convert the base unit to a selectable midand rear PTO driving assembly.

A further object of this invention is the provision of a PTO drivingassembly which is flexible in use.

A further object of the present invention is the provision of a PTOdriving assembly which allows conversion by removing one or more rearcovers from a single end of the transmission.

A further object of the present invention is the provision of a PTOdriving assembly which is inexpensive to manufacture, reliable, anddurable in use.

These and other objects will be apparent from the drawings, and thedescription and claims which follow.

SUMMARY OF THE INVENTION

The present invention relates to a vehicle transmission assembly whichincludes a power means, a clutch connected to the power means and havingan output power shaft, and a plurality of gears in substantialalignment. The gears include a first gear on the power shaft meshed witha second gear mounted on a first shaft. The second gear drives a thirdgear mounted on another idler shaft. The third gear drives a fourth gearmounted on a mid PTO shaft. A rear PTO shaft is operatively connected tothe first shaft. A three position selector assembly on the first shaftselectively powers the PTO shafts simultaneously or individually.

The present invention also provides an economical base unit having aplurality of gears meshed and aligned in a common vertical plane todrive only a mid PTO shaft. The base unit can be converted to theselectable mid and rear PTO arrangement described above by removing therear cover, rearranging some existing gears and spacers, and installinga conversion kit that includes a modified rear cover, a rear PTO shaftand a selector assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic diagram of the selectable mid and rearPTO shaft driving assembly of the present invention.

FIG. 2 is a partial vertical sectional view of the mid PTO (base unit)driving assembly of the present invention with the rear cover and casingshown in cross section and phantom lines, respectively.

FIG. 3 is an enlarged scale rear elevation schematic view of the gearsof the base unit assembly of FIG. 2 as seen with the rear cover removed.

FIG. 4 is a partial sectional view, similar to FIG. 2, but shows theconversion thereof to the selectable mid and rear PTO assembly ofFIG. 1. The selector is in a centered position wherein both the mid andrear PTO shafts are driven.

FIG. 5 is a cross-sectional view taken along line 5--5 in FIG. 4 andshows the means for selecting the PTO shaft(s) to be driven.

FIG. 6 is an enlarged scale schematic rear elevation view of the gearsof FIG. 4 as generally seen from the righthand side of FIG. 4 when therear covers are removed.

FIG. 7 is an enlarged scale top view of the clutch and rear PTO shaft asseen from the top of FIG. 4.

FIG. 8 is an enlarged scale elevational view of the selector of FIG. 4but with the selector in a position to drive only the mid PTO shaft.

FIG. 9 is a cross-sectional view taken along lines 9--9 in FIG. 8. FIG.9 is similar to FIG. 5, except the selector has been moved to the leftso only the mid PTO is driven.

FIG. 10 is a view similar to that of FIG. 8, except the selector hasbeen moved to the right so only the rear PTO shaft is driven.

FIG. 11 is a cross-sectional view taken along lines 11--11 in FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

One of the PTO shaft driving assemblies of the present invention isshown in simplified schematic form in FIG. 1. The PTO system 10 includesa power input shaft 12 which is drivingly connected to the input side ofelectromagnetic clutch 14. The output side of the clutch 14 has anoutput power shaft 16 extending therefrom. The output power shaft 16engages first gear means 18. The first gear means 18 is selectivelydrivingly connected to a mid PTO shaft 20, a second gear means 22, and arear PTO shaft 26 by selector means 24.

As best seen in FIG. 2, the power input shaft 12 and the output powershaft 16 are supported by bearings 28 and 30 in the casing 36 (shown inphantom lines) and a bearing 32 in a rear cover 34. Thus, the clutch 14is supported between the casing 36 and the rear cover 34.

Gears 38, 40, 42 and 44 are disposed and aligned in a common verticalplane (FIG. 2). The gears 38, 40, 42 and 44 are stacked on top of eachother so that their gear teeth mesh, as shown in FIG. 3. Gear 38 iscoupled or secured to the output power shaft 16 for rotation therewith.The top gear 38 and the second gear 40 mesh at their outer peripheries.

The gear 40 is mounted about a shaft 45 which is rotatably supported bybearings 46, 47. Preferably, spline means secure the gear 40 to theshaft 45 so that the gear 40 can be removed from the shaft 45 by slidingthe gear axially. The gear 42 is similarly fixed for rotation with theshaft 48, which is rotatably supported by bearings 50, 52. The gears 40,42 could be merely rotatably mounted on the shafts 45, 48 withoutdetracting from the invention. In that case, shafts 45, 48 might bereferred to as idler shafts.

The gear 44 is drivingly mounted on the mid PTO shaft 20. Again, asplined connection is preferred so that the gear 44 can be slid axiallyalong the mid PTO shaft 20 for removal and conversion purposes.

Bearings 54 and 56 in the casing 36 and the rear cover 34, respectively,rotatably support the mid PTO shaft 20. A lip seal 58 adjacent thebearing 54 in the casing 36 prevents fluid leakage and keepscontamination out. Hollow tubular spacers 60, 62 and 64 mount on theshafts 45, 48, and 20 to the right of each of the gears 40, 42 and 44,respectively, as shown in FIG. 2.

When the PTO assembly of this invention is utilized in a compact utilitytractor, a compact transaxle (not shown) can be located in the casing 36between the mid PTO shaft 20 and the clutch 14.

The configuration shown in FIG. 2 defines what will be referred to asthe base unit or "mid PTO only" configuration. The mid PTO shaft 20rotates whenever the output power shaft 16 of the clutch 14 rotates. Themid PTO shaft 20 ceases to rotate when the clutch 14 ceases to rotateshaft 16. The base unit is inexpensive to manufacture because the numberof parts is kept to a minimum. The rear cover 34 is relatively easy tomachine and is therefore economical to produce. Vertical space is alsoconserved because the four gears 38-44 can be kept to a fairly smalldiameter. Preferably, gears 38-44 are identical gears of the spur orpinion type.

FIGS. 4-11 show an optional configuration to which the originally builtbase unit can easily be converted. Of course, the optional configurationcan also be originally built on the assembly line, but the costs may behigher, as discussed above.

The original rear cover 34 (FIG. 2) has been replaced in FIG. 4 by amodified rear cover 34A. For reasons which will become apparent later,the spacers 62, 64 have been switched with the gears 42, 44,respectively, on the lower two shafts 48, 20. No new hardware isrequired for this switch, the positions of the spacers and the gears aremerely switched on the shafts.

A rear PTO cover 66 detachably mounts on the modified rear cover 34A.The rear PTO cover 66 has a bearing 68 mounted therein to rotatablysupport the PTO shaft 26 in conjunction with a second bearing 70 mountedin the casing 36. A lip seal 72 prevents the leakage of fluid fromaround the PTO shaft 26. A rear PTO gear 74 is drivingly connected tothe rear PTO shaft 26. As best seen in FIG. 6, the rear PTO gear 74 islaterally offset from the clutch output power shaft 16, shaft 45, shaft48, and the mid PTO shaft 20.

Referring again to FIG. 4, a selector means 76 is operatively interposedbetween the rear PTO gear 74 and the gears 42, 44 connected to the midPTO shaft 20. The selector means or assembly 76 includes an elongatedselector shaft 78 having ends rotatably supported by bearings 46, 47 inthe casing 36 and the rear PTO cover 66, respectively. A gear 40 issecured by splines or other suitable driving means to an intermediateportion of the selector shaft 78 for rotating it. A mid PTO drive gear80 is slidably and rotatably mounted on the selector shaft 78 adjacentthe gear 40. As best seen in FIG. 5, the mid PTO drive gear 80 has anoutwardly directed splined flange 82 thereon.

A ring or drive collar 84 is secured for rotation with the selectorshaft 78 adjacent the splined flange 82. The collar 84 has a splinedinside diameter for securing it to corresponding splines 86 on theselector shaft 78. Furthermore, the drive collar 84 has splines on itsoutside diameter which engage corresponding splines on the insidediameter of a selector ring 88 to rotate it. The selector ring 88includes an annular groove 90 centrally located along its outsidediameter.

A rear PTO drive gear 92 slidably mounts on the selector shaft 78adjacent the drive collar 84 and opposite the mid PTO drive gear 80. Therear PTO drive gear 92 includes a splined flange 94 adjacent the drivecollar 84. The rear PTO drive gear 92 extends under the selector ring 88when the selector ring is in the position shown in FIGS. 4-7 and 10-11.As best seen in FIG. 5, the gear 40 drives the selector shaft 78 and thedrive collar 84 thereon. The splined inside diameter of the selectorring 88 simultaneously engages the drive collar 84 and the mid and rearPTO drive gears 80, 92 through their respective splined flanges 82, 94.The mid PTO drive gear 80 then drives the gears 42, 44 and ultimatelyrotates the mid PTO shaft 20. Meanwhile, the rear PTO drive gear 92 hasa geared outer diameter which engages corresponding gears on the rearPTO gear 74 to drive the rear PTO shaft 26. Thus, when the selector ring88 is in the position shown in FIG. 5, both the mid and rear PTO shafts20, 26 are driven simultaneously and under the control of a singleclutch 14.

The selector ring 88 is positioned by a selector arm or yoke 96 whichextends into the annular groove 90 and partially around thecircumference of the selector ring 88 (see FIGS. 4, 6 and 7). Theopposite end of the yoke 96 rigidly attaches to a guide bracket 98. Theguide bracket 98 includes a hole 99 therein. A positioning shaft 100 isrigidly mounted in the hole 99. The positioning shaft 100 extendssubstantially parallel to the selector shaft 78. The ends of thepositioning shaft 100 are slidably journalled in the rear cover 34A andthe rear PTO cover 66, respectively. The end of the positioning shaft100 extending into the rear PTO cover 66 has three identical, equallyspaced annular grooves 102A, 102B, 102C therein (see FIG. 4).

A pin 104 pivotally attaches the guide bracket 98 to one end of a leverarm 106. As best seen in FIG. 6, a control shaft 108 is rigidly attachedto the other end of the arm 106 and journalled in one of the covers 34Aor 66. A lip seal 110 prevents the leakage of oil around the controlshaft 108 and keeps contamination out.

Referring again to the positioning shaft 100, a spring loaded ball ordetent 112 mounts in the cover 66 and. yieldably extends into engagementwith one of the annular grooves 102A, 102B or 102C, depending upon theaxial position of the positioning shaft 100.

In regard to the operation of the invention, it should be firstunderstood that no rotation of either the mid or rear PTO shafts 20, 26takes place until the electromagnetic clutch 14 allows the power outputshaft 16 to be rotated by the power means 12. The power output shaft 16provides driving power to the gear 38, which also transmits power on theselector shaft 78 via the gear 40.

The control shaft 108 is connected by conventional linkage (not shown)to a lever or similar control means within the reach of the vehicleoperator. When the control shaft 108 is rotated so that the positioningshaft 100 and the spring loaded detent 112 are in the positions shown inFIGS. 4-5, both the mid and rear PTO shafts 20 and 26 will be rotatedbecause the splines on the drive collar 84, the drive gears 80, 92, andthe selector ring 88 are intermeshed. In FIGS. 4 and 5, the detent 112is in the groove 102B.

When the control shaft 108 is rotated in a counterclockwise direction,as shown in FIG. 8, the positioning shaft 100 moves to the left and thedetent 112 is disposed in the groove 102C as shown. Thus, the yoke 96also moves to the left, which forces the selector ring 88 to the left,as shown in FIG. 9. In this position, the selector ring 88 engages onlythe drive ring 84 and the splines 82 on the mid PTO drive gear 80. Therear PTO drive gear 92 is not engaged by the selector ring 88 in thisposition. Therefore, no rotary power will be transmitted to the rear PTOshaft 26 through the gear 74. The rear PTO drive gear 92 will simplyrest loosely around the rotating selector shaft 78.

In FIG. 10, the control shaft 108 has been rotated in a clockwisedirection, which forces the positioning shaft 100 and the yoke 96rigidly attached thereto to move to the right until the detent 112 isdisposed in the groove 102A. As best seen in FIG. 11, the selector ring88 then engages the drive collar 84 and the splines 94 on the rear PTOdrive gear 92. The rear PTO drive gear 92 rotates with the selector ring88 and the drive shaft 78 so as to provide rotary power through the gear74 to the rear PTO shaft 26. However, the splines 82 on the mid PTOdrive gear 80 are not engaged by the selector ring 88. The gear 80loosely rests on the selector shaft 78 as it rotates. Therefore, norotary power is supplied to the mid PTO shaft 20 through the gears 80,42 and 44, although the gear 40 does rotate and drive the selector shaft78.

Thus, the PTO assembly of this invention provides a three-positionselector means 76 which allows rotary power to be transmitted to a midPTO shaft only, mid and rear PTO shafts simultaneously, or to a rear PTOshaft only, depending upon the position of the selector means.

Another aspect of this invention is that the above-described structureprovides for a unique method of converting from a base unit having onlya mid PTO shaft 20 (FIGS. 2-3), to an optional unit having a mid PTOshaft 20 and a rear PTO shaft 26 selectively driven by a selector means76 (FIGS. 4-11). To accomplish the conversion, one addresses the rear ofthe base unit shown in FIG. 2. Access to the top, front, sides, orbottom of the unit is not necessary. This is particularly advantageousbecause these areas are not very accessible once the unit has beeninstalled in a tractor. However, the rear of the unit is generallyaccessible in most tractor installations.

Next, the person doing the conversion removes the rear cover 34 and setsit aside. The bearings 52, 56 are removed from the lower shafts 48, 20respectively. Then, the spacers 62, 64 and gears 42, 44 are removed fromthe shafts 48, 20. The spacers 62, 64 are then reinstalled on the shafts48, 20 in the positions which the gears 42, 44 previously occupied.Thus, the spacers 62, 64 and the gears 42, 44, respectively, areinterchanged or reversed. The changed positions can be seen in the lowerportion of FIG. 4. To this point, no new hardware has been added.

In the conversion process, the shaft 45 is replaced with the selectorshaft 78 and the associated components mounted thereon, as shown in FIG.5. The bearings 46 and 47 can be either reused or replaced. Next, a newrear cover 34A is installed in place of the old rear cover 34. Thepositioning shaft 100, the yoke 96 and the guide bracket 98 are alsoinstalled in the rear cover 34A, as shown in FIGS. 4 and 6. Preferably,the yoke 96 extends into the slot 90 on the selector ring 88. Thecontrol shaft 108 is inserted into the rear cover 34A and rigidlyattached to the lever arm 106. The lever arm 106 is pivotally connectedto the guide bracket 98 by inserting the pin 104 into the hole 99.Finally, the seal 110 is pressed into the rear cover 34A around thecontrol shaft 108.

Referring again to FIG. 4, the rear PTO shaft assembly, comprising theshaft 26, the bearings 68, 70 and the gear 74 is installed. Then, therear PTO cover 66 is added and the lip seal 72 is installed around theshaft 26. Finally, the selector means 76 is adjusted by moving thecontrol shaft 108 until the positioning shaft 100 positions the selectorring 88 with the yoke 96 into the position shown in FIG. 5. In this"centered" position, rotary power can be transmitted to both the mid andrear PTO shafts 20, 26. A spring loaded detent or ball 112 is theninserted into a receiving hole in one of the rear covers 34A or 66. Thespring loaded detent 112 yieldably protrudes into the center groove 102Bon the positioning shaft 100. The annular grooves 102A, 102B and 102Care disposed on the positioning shaft 100 so that the selector 88 can beset in the three positions shown in FIGS. 5, 9, and 11.

The conversion kit can include a loose, unassembled collection of theparts necessary for the conversion or the kit can include a preassembledmodule containing the necessary parts.

Therefore, the present invention provides a quick and relatively easymethod of converting from a low cost base unit having only a mid PTOshaft to an optional configuration having both a mid and rear PTO shaft.This method does not require the entire transmission to be removed andrebuilt, nor does it require access to anything but the rear of thetransmission.

Therefore, the present invention at least achieves its statedobjectives.

What is claimed is:
 1. A method of converting a transmission base unithaving a rotatable first PTO shaft into an optional configurationtransmission unit having both a selectively rotatable first PTO shaftand a selectively rotatable second PTO shaft, comprising:taking a baseunit having a rotatable first PTO shaft drivingly connected to a powermeans by plurality of gears, connecting a multi-position selectorassembly to the gears to permit the first PTO shaft and the second PTOshaft to be simultaneously or individually powered.
 2. The method ofclaim 1 wherein some of the gears are moved from a vertically alignedposition to a vertically offset position to accommodate the connectionof the multiposition selector assembly.
 3. The method of claim 2 whereina first cover on the transmission base unit is removed from thetransmission base unit before the selector assembly is installed, and isreplaced by a second cover to accommodate the connection of themulti-position selector assembly and the movement of at least some ofthe gears.
 4. The method of claim 2 wherein at least some of the gearsare moved by interchanging the longitudinal position of some of thegears with adjacent positions of spacer elements upon shafts upon whichthe gears and the spacer elements are mounted.